Chapter 7: Physics Flashcards
What is Physics?
The science that examines matter, space and time.
What is the study of an electric charge at rest?
electrostatics
What is the study of an electric charge in motion?
electrodynamics
What are the two kinds of electric charges?
positive and negative
What is electrostatic force?
the force between particles that is cause by their electric charge.
An electrostatic force can be repulsive or attractive, what are the differences between these.
Attractive -2 charges pull toward, happens when 2 charges are of the opposite type. Repulsive -2 charges push away, happens when 2 electric charges are the same type
Materials and objects are made up of atoms and molecules that are electrically neutral. What does electrically neutral mean?
Having neither positive nor negative charge because they have an equal number of positive charges and negative charges.
Is it possible to give a normally neutral material an electric charge?
yes
Give an example of how to give a normally neutral material an electric charge?
Rub two objects together
If two materials with opposite charges are brought close to each other, they may generate a spark (movement of electrons through the air) What is this called?
Static electricity
What causes lighting?
Clouds pass each other during storm, and exchange electrons.
What are free electrons and what material and they only present in?
electrons which haven broken away from their parent electron. They are only present in metal.
What is an electric current?
A “river” of moving electrons, forced to move by an electromagnetic field.
Give an example of an insulator (non-conductor, high resistance)
rubber, plastic, glass, paper.
Give an example of conductor(low resistance)
Most metals
What makes semiconductors different?
We can control their conductivity, we can switch it back and forth whenever we want.
Copper wire is an example of what?
a good conductor- current is able to flow easily along
Plastic is an example of what?
insulator - electrical charge can not pass through
Is the human body a good conductor? Why or Why not?
Yes because it is made up of mostly water which is a good conductor.
What are some good safety practices when working around electricity.?
Wearing safety cloths, gloves made of insulating materials and standing on a insulating surfaces. These will not allow current to flow through a person’s body.
When electricity passes through an object what happens?
it heats up
Do low resistance materials get hot?
yes very hot can reach more than 1000 C. and these materials can start to glow.
Name three types of electric light bulbs used today
Incandescent light bulbs, Compact fluorescent lamps CFL & LED light Emitting Diode.
Describe how an incandescent light bulb works.
current flows through a hot metal conductor
Describe how an compact fluorescent lamp works.
current flows through a gas
What is a tungsten filament?
most important part of a incandescent light bulb which is a very good conductor which does not melt easily and glows brightly at high temps.
What makes the glowing last longer in an incandescent bulb?
Inert gas which doesn’t react with tungsten is enclosed in a glass bulb.
Which releases less heat, making it more efficient, an incandescent bulb or compact florescent ?
Compact florescent because the current flows through a gas instead of a metal conductor.
What is the downside of compact florescent bulbs?
CFLS contain mercury (toxic substance) so they need to be handled and disposed of safely.
How does an LED, light emitting diode work?
Movement of electrons in a semiconductor material, as the electrons move they release energy in the form of photons.
What are photons?
small entities which are the basic unit of light
Give some examples of LEDS
digital clocks, tv remotes, traffic lights.
Give some advantages of LEDs
lower energy consumption, longer lives, smaller size, durability.
What do you call the way in which two different chemical compounds exchange electrons, in turn creating a current?
Electrochemical reaction.
What is Bioelectrogenesis?
Generation of electricity by living organisms.
Give example of animals that can produce electricity?
Jellyfish, rays, electric eels.
How do electric eels produce electricity?
They have 3 organs that produce electricity. They make up 4/5th of the eels body.
What is electrolocation?
It is used detect objects around you, for example some fish have this capacity and can sense objects around them via electricity in their bodies.
Can light be converted to electricity?
Yes
Describe the photovoltaic effect?
When special materials called PHOTOVOLTAIC materials are exposed to light they create an electric current.
Give an example of a photovoltaic material?
Solar cells used in solar panels.
What percentage of the world’s electricity is currently generated using solar power?
Less than 1%
What is electromagnetic induction?
Production of an electric current across a conductor moving through a magnetic field.
How does a generator work?
By rotating electromagnetic coils inside a ring of natural north & south magnets
How much electricity worldwide is generated using heat?
80%
Where does most of the heat (2/3) used to generate electricity come from.
Burning of fossil fuels such as coal, oil, and natural gas.
How does thermal generation work?
Heat is used to exchange liquid water into steam. The movement of the steam causes the turbine to spin the rotor.
What is the main disadvantage of fossil fuels?
Large amounts of carbon dioxide, a greenhouse gas are produced as a by-product of burning fuels.
Nuclear power plants use thermal energy, but what do they use instead of fossil fuels?
Uranium. A heavy naturally radioactive element.
What is Fission?
A reaction in which atoms split apart. When they split apart there is a huge release of energy in the form of steam.
How does nuclear power work?
The super heated steam flows to turbines which are connected to a shaft that spins. The shaft runs through the turbine into the generator.
Does Nuclear power create carbon dioxide emissions?
No, but there is radioactive spent fuel that must be stored safely.
What is Hydroelectricity?
Production of electricity using moving water.
What percentage of electricity in Canada used is Hydroelectricity? What percentage of the worlds?
2/3 Canada’s electricity = Hydroelectricity
16% Worlds electricity = Hydroelectricity
Name the main components of a Hydroelectric system?
penstock (pipes that direct the water), turbine & generator & may include a dam.
How does Hydroelectricity work?
In the pipes, potential energy (stored) is converted into kinetic energy (motion) as a result of the change of height as the water descends from the reservoir through the intake to the turbine. The kinetic energy of the moving water is then converted into mechanical energy when it spins the turbine. The turbine turns a shaft which is attached to the rotor in the generator which is housed in the power station.
What is a dam used for?
To increase the pressure and control the volume of water so that more electricity can be generated.
What is a disadvantage of a dam?
A dam can flood land which can then not be used for other things such as farming. Flooding can also cause ecosystem damage such as loss of habitat for animals. Methane (greenhouse gas) can also be produced as a result of flooding.
What percentage of the worlds electricity is generated using wind power?
1%
What is a wind turbine?
A Machine that converts kinetic (wind) energy into electrical energy using very large propeller blades and a turbine-generator system that is mounted on tall towers either on land or over water.
Name three renewable sources of energy.
HYDROELECTRICITY (does not consume the water) WIND POWER (produce electricity without significant carbon dioxide emissions from fuel used) BIOFUELS (new plants can be grown to take the place of one that were processed into fuel)
Where is the tallest turbine in Canada located?
Alberta- called the Weather Dancer, it can produce up to 2960 megawatt-hours of power in one year.
Name a disadvantage of Wind turbines.
They only run when the wind is blowing.
What are biofuels made from?
Plants - crops
Give an example of a bio fuel.
Corn - grown in a field, harvested and then processed into ethanol.
What is ethanol?
Ethanol is an alternative to gasoline and can be burned in the engine of a car just like gasoline.
Name a advantage of Biofuels.
While crops are growing they absorb carbon dioxide. This offsets the carbon dioxide release from burning the biofuel once its processed.
What was Canada’s first day producing electricity from nuclear energy and where did it take place?
June 4, 1962, Rolphton, Ontario.
How much of Ontario’s power comes from Nuclear Power today?
50%
What is energy conservation?
Not using any electricity if you don’t need to.
What are some benefits from energy conservation?
Reduces our environmental impact and saves money.
How can we conserve energy?
Read a book instead of playing video game or watching tv. Open curtains instead of turning on light. Turn lights off when leaving room. Turn off electronics when not in use. Use energy-efficient devices. Try not to use as much electricity at peak times.
What is the Energy Star symbol?
Energy efficiency seal of approval found of electronics.
What is baseload electricity?
Electricity that is constant. Steady stream of electricity that is always consumed day and night. Usually provided by hydroelectric and nuclear plants which can produce large amounts of electricity efficiently and reliably.
What are the peak demand times for electricity?
4:00 pm - 7:00pm
